In general, round ducts are presently made by machines that form flat metal into a round duct. First the flat round duct material is passed though a roll-former that forms seams on the longitudinal length of the yet to be rolled round duct flat material. The flat round duct material is then typically rolled from the flat sheet that previously had seams applied to it into round duct in a rolling machine that can be either motorized or non-motorized, and manually or computer controlled. The seam is then manually interlocked to lock the seam closed thus creating a completed manufactured round duct.
Spiral ducts are presently formed from narrow 5 inch to 6 inch wide coil stock material of about 26 gauge to about 16 gauge thick, by a machine that is computer controlled, that automatically forms the diameter of the spiral duct while simultaneously creating seams to both edges of the coil stock material that then become interlocked in the machine thus creating spiral seamed round duct.
The attaching structures may be made by computer controlled flat X and Y plasma cutting machines. They are then manually formed and assembled.
After the attaching structures and the round or spiral ducts are manufactured, the cutouts for the must be cut into the round or spiral ducts.
Presently the cutouts are manually located on the round or spiral ducts by placing a template or the attaching structure to the round or spiral ducts and then manually tracing the shape of the needed cutout with a marker or pen.
Upon marking the round or spiral ducts the holes are then cut manually by using a scissors, jigsaw, or a hand held plasma torch.
It is very difficult and time consuming to measure and layout the cutouts into the round or spiral ducts accurately using this method.
Following are some examples of typical layouts:
First example: two cutouts at zero degrees of the longitudinal axis and 10 inches from the first end of the round or spiral ducts with the second cutout spaced at 40 inches from the first cut out on the round or round spiral ducts.
Second example: two cutouts one cutout at zero degrees and 10 inches from the first end of the round or spiral ducts with the second cutout at 180 degrees with the second cutout being measured and spaced at 40 inches from the first cutout.
Third example: three cutouts one cutout at zero degrees and 10 inches from the first end of the round or spiral ducts with the second cutout at 180 degrees with the second cutout being measured and spaced at 40 inches from the first cutout. Third cutout at 90 degrees being measured and spaced at 20 inches from the first cutout.
Fourth example: two cutouts one cutout at zero degrees and 10 inches from the first end of the round or spiral ducts with the second cutout at 180 degrees with the second cutout being measured and spaced at 40 inches from the first cutout and a miter cut of 30 degrees made to the second end of the round or round spiral duct.
The placing of the cutouts and trimming ends on round or spiral duct manually is labor intensive, time consuming, and can result in inaccuracies in many directions that often result in wasted materials and labor.